Formaldehyde dissipation mechanism of active alginate gel and its application in deep air purification

Abstract

It is very important to purify low level formaldehyde pollution in indoor air by an efficient and low-cost material. In this research, an environmentally friendly material (names as ACA) was prepared by fixing the active component in cactus stem with the three-dimensional network structure of calcium alginate gel. It was observed by a scanning electron microscopy that plant active substances were dispersed and embedded in the three-dimensional network structure gaps of calcium alginate. The large surface area and strong hydrophilicity of the calcium alginate gel indicate a strong ability to capture low level formaldehyde in the airflow, while there is a rapid degradation ability of plant active substances to formaldehyde fix by gel. The prepared material was found an efficient and deep removal ability to formaldehyde in airflow. Results showed that removal rate reached to 88.64 ~ 91.57% at the airflow residence time of 0.13 s and the formaldehyde level in unpurified airflow in the range of 0.081 ~ 0.328 mg·m-3, and the formaldehyde level in purified airflow can below 0.02 mg·m-3. After continuously working for 63 hours, the removal rate was still 64.74 ~ 73.56%, and the formaldehyde level in purified airflow was 0.04 ~ 0.08 mg·m-3. The removal efficiency of ACA-cactus to formaldehyde in airflow was up to 1387.66 mg·h-1·kg-1 (dry weight of gel), and the corresponding maximum airflow purification capacity was 6000 m3·h-1·kg-1. Similar to a bioreactor, enzymatic mild oxidation of plant active components plays a dominant role in the removal of formaldehyde by ACA. This research provides a new idea for the deep purification of formaldehyde in the air and has a huge application potential.